265 fuel tank replacement

[Sardinia306Canyon]

No evidence of fuel in the bilge fore or aft, pulled deck plates and tops of tanks, fuel fill and lines look good.

Thats normal in the beginning when pin holes develop.
The pin hole is so small that gasoline seat out and do the smell, but no fuel in bilge water.
As SkunkBoat wrote, holes are mostly on the lower part and in the beginning the weight of the fuel tank let fuel sweat thru the pinhole but later half full it stops. And check the connections on top, as you replaced the fuel senders the culprit may be there.
Once the tank is out then replace all except the new fuel senders and pull also the second one to verify or replace both, you don't want to do this again soon. I understand that replacing both tanks will be much more expensive, but if one leaks, often the other will leak soon too and you have tu start over.
Chris

 

[Sea Shift]

How did you know that it was leaking? Actual fuel in bilge or smell?

Yes I had fuel in my bilge. I removed the hatch and this is what i found. Obviously water build up and alge/gooo. Once I cleaned it off there was a 1/4" hole on the top. Im sure the under side has the classic pinholes too. Ive since drained the tank.

 

[Sardinia306Canyon]

Urghhhh, thats a nasty mess and i feel sorry for that as i am doomed with leaking fuel tanks for different reasons.

As far i was reading here GW issued a notice that fuel tanks should be hosed down every now and then to avoid that saltwater dripping from the notoriously leaking pie plates on the tank and create this mess and sooner and later a hole.

I was also wondering if i should try to "paint" the area under the pie plate and full of elbows, fuel sender and cables with the blue sticky marine grease to limit that a bit.

In the moment i just hose down the tanks and check pie plate's o-ring and consider to install new ones, just for peace of mind.

If i would have to change fuel tanks i probably would make the top slightly curved so that water can't poodle and will run down.

Chris

 

[drbatts]

Same thing happened to the fuel tanks a couple of my friend's boats(non gradys). The deck plates leaked, and water pooled on the tank. The holes in the tank were right under the deck plates. The deck plates will also leak from inadequate caulking at the factory and/or the caulking breaking down. Every deck plate I have replaced on my gradys and previous boats, when I remove the old deck plates there is not a lot of caulk and its obvious there is water getting through.

 

[SeaVee]

So, I was at a tournament party a few days ago. My neighbor is looking for a tank fabricator for 2 saddle tanks for his 25 SeaVee inboard. I asked a well known Carolina custom builder who he might suggest. He said he’s switched to Mueller plastic tanks on all his builds and refits. He builds custom Carolina boats from 25 to over 50 feet, plus tons of refits. He said you might not get the exact dimensions of your current tanks but generally you can get close enough, and the cost savings are enormous. Thought that was interesting.

 

[Ekea]

So, I was at a tournament party a few days ago. My neighbor is looking for a tank fabricator for 2 saddle tanks for his 25 SeaVee inboard. I asked a well known Carolina custom builder who he might suggest. He said he’s switched to Mueller plastic tanks on all his builds and refits. He builds custom Carolina boats from 25 to over 50 feet, plus tons of refits. He said you might not get the exact dimensions of your current tanks but generally you can get close enough, and the cost savings are enormous. Thought that was interesting.

isnt there generally a size limit for the poly tanks? the issue with larger poly tanks was the lack of internal baffling

 

[Sardinia306Canyon]

isnt there generally a size limit for the poly tanks? the issue with larger poly tanks was the lack of internal baffling

Yep, it is.
The biggest moeller tank is 230 gallons, but they may do bigger special tanks after manufacturer specifications.
https://www.moellermarine.com/off-the-shelf/fuel-tanks/permanent-fuel-tanks/
They have baffels, but not completely closed ones, i guess half of the baffle is on each side.

Chris